This isn't Arduino per se, but just wondering if anyone's come across this before - I was initially using the VisualMicro IDE to upload to a Tiny85 using a TinyISP programmer, but have now removed the IDE from from the suspects list and can reproduce with just avrdude and my compiled .hex

I get the verification failures usually when the programmer's sck clock is too fast when the attiny internal clocking set below 1.5 MHz. You can usually fix this by slowing down the sck clock signal. A few programmers like the usbtiny can be told to slow down with an avrdude -B option.

Alternatively, if you are not able to use the -B option in avrdude, some programmers do not support that option, or you are not able to add that to the command sequence. You can try a programmer like the USBasp which will support a hardware jumper setting to use a slow sck clock. But be aware that there are many different versions of the USBasp and some do not support the hardware jumper setting.

I tried the 5.11.1 patch last night but no luck - problem still exists. I have just realised that this is still a 'virginal' Tiny85 - the fuses have not yet been set (due to a possible issue with VisualMicro) so that may have a bearing. it's supposed to be on 8Mhz internal clock but is currently on 1Mhz I think. I'll set teh fuses separately tonigth and see if that changes anything...

I don't think it's the programmer as it worked fine with avrdude 5.10 and has been working for a couple of years. Don't have another '85 but I do have a '2313 so I'll try that as soon as I get a chance again